|Systematic (IUPAC) name|
|(6aR)- 4,6,6a,7,8,9,10,10a- octahydroindolo [4,3-fg] quinoline|
Ergoline is a chemical compound whose structural skeleton is contained in a diverse range of alkaloids including a few psychedelic drugs (ololiuhqui, LSD). Ergoline derivatives are used clinically for the purpose of vasoconstriction (5-HT1 receptor agonists—ergotamine) and in the treatment of migraine (used with caffeine) and Parkinson's disease, some are implicated in the disease ergotism, causing convulsive and gangrenous symptoms.
In addition to the naturally occurring ergonovine (used as an oxytocic) and ergotamine (a vasoconstrictor used to control migraine), synthetic derivatives of importance are the oxytocic methergine, the anti-migraine drugs dihydroergotamine and methysergide, hydergine (a mixture of dihydroergotoxine mesylates, INN: ergoline mesylates), and bromocriptine, used for numerous purposes including treatment of Parkinson's disease. Newer synthetic ergolines used for Parkinson's disease include pergolide and lisuride.
Perhaps the most famous ergoline derivative of all is the psychedelic drug LSD. Ergometrine and ergotamine are included as table I precursors in the United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances. 
The relationship between these compounds is summarized in the following structural formula and table of substitutions.
These compounds have a tripeptide structure attached to the basic ergoline ring, in the same location as the amide group of the lysergic acid derivatives. This tripeptide moiety contains an unusual cyclol bond >N-C(OH)< at the juncture between the two lactam rings. Some of the important ergopeptines (also known as ergopeptides) are summarized below. In addition to the following ergopeptines, a commonly encountered term is ergotoxine, which refers to a mixture of equal proportions of ergocristine, ergocornine and ergocryptine.
Some synthetic ergoline derivatives do not fall easily into any of the above groups. Some examples are:
Ergoline alkaloids is found in lower fungi and two species of flowering plants: the Mexican species Rivea corymbosa and Ipomoea violacea of the Convolvulaceae (morning glory) family, the seeds of which were identified as the psychedelic plant drugs known as "ololiuhqui" and "tlitliltzin". The principal alkaloids in the seeds are ergine and its optical isomer isoergine, with several other lysergic acid derivatives and clavines present in lesser amounts. The Hawaiian species Argyreia nervosa includes similar alkaloids. It is possible, though not proven, that ergine or isoergine are responsible for the hallucinogenic effects. There may be a fungal origin of the ergoline alkaloids also in the Convolvulaceae. Like the ergot alkaloids in some monocot plants, the ergoline alkaloids found in the plant Ipomoea asarifolia (Convolvulaceae) are produced by a seed-transmitted epiphytic clavicipitaceous fungus.
Ergoline alkaloids were first isolated from ergot, a fungus that infects grain and causes the disease ergotism. Ergot also has a long history of medicinal use, which led to attempts to characterize its activity chemically. This began in 1907 with the isolation by G. Barger and F. H. Carrin of ergotoxine, so-named since it appeared to exhibit more of the toxicity of ergot than its therapeutic qualities. With the isolation of ergotamine in 1918 by A. Stoll came the first therapeutic use of isolated ergoline alkaloids.